Method and apparatus for random access in a wireless communication system

ABSTRACT

Embodiments of the present disclosure provide methods, apparatuses and computer program products for random access in a wireless communication system. A method in a terminal device comprises receiving a random access configuration from a network device, the random access configuration including information for determining a set of candidate subframe numbers and a set of candidate system frame numbers for transmitting a random access preamble; transmitting the random access preamble in a subframe within a radio frame, the subframe being associated with a subframe number, and the radio frame being associated with a system frame number, wherein the subframe number is selected from the set of candidate subframe numbers, and/or, the system frame number is selected from the set of candidate system frame numbers t, based on a size of a Message 3 (Msg3) to be transmitted by the terminal device to the network device during the random access.

This application is a 35 U.S.C. § 371 national phase filing ofInternational Application No. PCT/CN2018/075203, filed Feb. 5, 2018,which claims the benefit of International Application No.PCT/CN2017/078200, filed Mar. 24, 2017, the disclosures of which areincorporated herein by reference in their entireties.

TECHNICAL FIELD

The non-limiting and example embodiments of the present disclosuregenerally relate to a technical field of wireless communication, andspecifically to methods, apparatuses and computer program products forrandom access in a wireless communication system.

BACKGROUND

This section introduces aspects that may facilitate better understandingof the disclosure. Accordingly, the statements of this section are to beread in this light and are not to be understood as admissions about whatis in the prior art or what is not in the prior art.

In wireless communication systems, a terminal device has to setup aconnection with a network node before transmitting any data to thenetwork node. A procedure for a terminal device to request a connectionsetup is commonly referred to as random access (RA). A terminal devicemay perform the random access on a carrier which it determines to campon based on a result of cell search. The random access may be performedeither using a contention based scheme which requires a terminal deviceto select a resource for the random access from a shared resource poolor a contention-free scheme which allows the terminal device to performthe random access using an assigned dedicated resource. A contentionbased scheme requires a mechanism for a network node to resolve anycontention due to multiple terminals trying to access the network usinga same random-access resource.

In a random access procedure, a terminal device may transmit a randomaccess preamble (also referred to as a physical random access channel(PRACH) preamble, a preamble, a RACH request, or Msg1) to a networkdevice. Transmission of the random access preamble may use a resourcedetermined based on PRACH Configuration Index. More details on theseparameters and their values may be found, for example, in 3GPP TS 36.211v10.1.0, Section 5.7 Physical random access channel. In response toreceiving the random access preamble, the network device transmits, tothe terminal device a random access response (RAR) message (which mayalso be referred to as Msg2) carrying a timing advance (TA) command toadjust the UL transmission timing of the terminal device. The terminaldevice transmits, to the network device, a message 3 (which may also bereferred to as Msg3) using the resource assigned/scheduled by thenetwork device via the RAR message. In response to the received Msg3,the network device may transmit a contention-resolution message (whichmay also be referred to as Msg4) to the terminal device.

SUMMARY

Current design for random access may not be suitable for some newwireless communication systems, for example, the fifth generation (5G)or New Radio (NR). In order to provide a more efficient random accessprocedure, methods, apparatuses and computer program products areprovided in the present disclosure. It will be appreciated thatembodiments of the present disclosure are not limited to NR systeminformation transmission/reception in a 5G system, but could be morewidely applied to any wireless communication system where similarproblems exist.

Various embodiments of the present disclosure mainly aim at providingmethods, apparatuses and computer program products for informationtransmitting and receiving. Other features and advantages of embodimentsof the present disclosure will be understood from the followingdescription of various embodiments when read in conjunction with theaccompanying drawings, which illustrate, by way of example, theprinciples of embodiments of the present disclosure.

In a first aspect of the disclosure, there is provided a method in aterminal device. The method comprises: receiving a random accessconfiguration from a network device, the random access configurationincluding information for determining a set of candidate subframenumbers and a set of candidate system frame numbers for transmitting arandom access preamble; transmitting the random access preamble in asubframe within a radio frame, the subframe being associated with asubframe number, and the radio frame being associated with a systemframe number, wherein the subframe number is selected from the set ofcandidate subframe numbers, and/or, the system frame number is selectedfrom the set of candidate system frame numbers, based on a size of aMsg3 to be transmitted by the terminal device to the network deviceduring the random access.

In some embodiments, the random access preamble may be selected from aset of candidate preambles based on the size of the Msg3.

In a further embodiment, the terminal device may receive a furtherconfiguration of a set of thresholds with respect to the size of theMsg3 and a mapping relationship configuration between the set ofthresholds and PRACH transmissions; and determining a PRACH transmissionbased on the set of thresholds to indicate the size of the Msg3 to thenetwork device.

In a second aspect of the disclosure, there is provided a method in anetwork device. The method comprise: transmitting a random accessconfiguration to a terminal device, the random access configurationincluding information for determining a set of candidate subframenumbers and a set of candidate system frame numbers for transmitting arandom access preamble; receiving, from the terminal device, a randomaccess preamble in a subframe within a radio frame, the subframe beingassociated with a subframe number, and the radio frame being associatedwith a system frame number, wherein the subframe number is selected fromthe set of candidate subframe numbers, and/or, the system frame numberis selected from the set of candidate system frame numbers, based on asize of a Msg3 to be transmitted by the terminal device to the networkdevice during the random access; and determining the size of the Msg3,to be transmitted by the terminal device during the random access, basedon at least one of the subframe number and the system frame number.

In some embodiments, the network device may determine the size of theMsg3 further based on the random access preamble.

In a third aspect of the disclosure, there is provided a terminal devicefor random access in a wireless communication network. The terminaldevice comprises a processor and a memory, said memory containinginstructions executable by said processor whereby said apparatus isoperative to: receive a random access configuration from a networkdevice, the random access configuration indicating a set of candidatesubframe numbers and a set of candidate system frame numbers fortransmitting a random access preamble; transmit the random accesspreamble in a subframe within a radio frame, the subframe beingassociated with a subframe number, and the radio frame being associatedwith a system frame number, wherein the subframe number is selected fromthe set of candidate subframe numbers, and/or, the system frame numberis selected from the set of candidate system frame numbers, based on asize of a Msg3 to be transmitted by the terminal device to the networkdevice during the random access.

In a fourth aspect of the disclosure, there is provided a network devicefor random access in a wireless communication network. The networkdevice comprises a processor and a memory, said memory containinginstructions executable by said processor whereby said apparatus isoperative to: transmit a random access configuration to a terminaldevice, the random access configuration indicating a set of candidatesubframe numbers and a set of candidate system frame numbers fortransmitting a random access preamble;

receive, from the terminal device, a random access preamble in asubframe within a radio frame, the subframe being associated with asubframe number, and the radio frame being associated with a systemframe number; wherein the subframe number is selected from the set ofcandidate subframe numbers, and/or, the system frame number is selectedfrom the set of candidate system frame numbers, based on a size of aMsg3 to be transmitted by the terminal device to the network deviceduring the random access, and determine the size of the Msg3, to betransmitted by the terminal device during the random access, based on atleast one of the subframe number and the system frame number.

In a fifth aspect of the disclosure, there is provided a computerreadable storage medium having a computer program product embodiedthereon, the computer program product including instructions which, whenexecuted on at least one processor, cause the at least one processor tocarry out any method according to the first aspect of the presentdisclosure.

In a sixth aspect of the disclosure, there is provided a computerreadable storage medium having a computer program product embodiedthereon, the computer program product including instructions which, whenexecuted on at least one processor, cause the at least one processor tocarry out any method according to the second aspect of the presentdisclosure.

According to various aspects and embodiments as mentioned above,efficiency of the random access procedure may be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and benefits of variousembodiments of the present disclosure will become more fully apparentfrom the following detailed description with reference to theaccompanying drawings, in which like reference numerals or letters areused to designate like or equivalent elements. The drawings areillustrated for facilitating better understanding of the embodiments ofthe disclosure and not necessarily drawn to scale, in which:

FIG. 1 illustrates an example wireless communication network in whichembodiments of the present disclosure may be implemented;

FIG. 2 illustrates a flowchart of a method implemented at a terminaldevice according to an embodiment of the present disclosure;

FIG. 3 illustrates a flowchart of a method implemented at a networkdevice according to an embodiment of the present disclosure; and

FIG. 4 illustrates a simplified block diagram of an apparatus that maybe embodied as/in a network device, and an apparatus that may beembodied as/in a terminal device.

DETAILED DESCRIPTION

Hereinafter, the principle and spirit of the present disclosure will bedescribed with reference to illustrative embodiments. It should beunderstood that all these embodiments are given merely for one skilledin the art to better understand and further practice the presentdisclosure, but not for limiting the scope of the present disclosure.For example, features illustrated or described as part of one embodimentmay be used with another embodiment to yield still a further embodiment.In the interest of clarity, not all features of an actual implementationare described in this specification.

References in the specification to “one embodiment,” “an embodiment,”“an example embodiment,” and the like indicate that the embodimentdescribed may include a particular feature, structure, orcharacteristic, but it is not necessary that every embodiment includesthe particular feature, structure, or characteristic. Moreover, suchphrases are not necessarily referring to the same embodiment. Further,when a particular feature, structure, or characteristic is described inconnection with an embodiment, it is submitted that it is within theknowledge of one skilled in the art to affect such feature, structure,or characteristic in connection with other embodiments whether or notexplicitly described.

It shall be understood that although the terms “first” and “second” etc.may be used herein to describe various elements, these elements shouldnot be limited by these terms. These terms are only used to distinguishone element from another. For example, a first element could be termed asecond element, and similarly, a second element could be termed a firstelement, without departing from the scope of example embodiments. Asused herein, the term “and/or” includes any and all combinations of oneor more of the associated listed terms.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be liming of exampleembodiments. As used herein, the singular forms “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises”, “comprising”, “has”, “having”, “includes” and/or“including”, when used herein, specify the presence of stated features,elements, and/or components etc., but do not preclude the presence oraddition of one or more other features, elements, components and/orcombinations thereof.

In the following description and claims, unless defined otherwise, alltechnical and scientific terms used herein have the same meaning ascommonly understood by one of ordinary skills in the art to which thisdisclosure belongs.

As used herein, the term “wireless communication network” refers to anetwork following any suitable wireless communication standards, such asNR, Long Term Evolution (LTE), LTE-Advanced (LTE-A), Wideband CodeDivision Multiple Access (WCDMA), High-Speed Packet Access (HSPA), andso on. Furthermore, the communications between network devices in thewireless communication network may be performed according to anysuitable generation communication protocol, including, but not limitedto, Global System for Mobile Communications (GSM), Universal MobileTelecommunications System (UMTS), Long Term Evolution (LTE), and/orother suitable, and/or other suitable the first generation (1G), thesecond generation (2G), 2.5G, 2.75G, the third generation (3G), thefourth generation (4G), 4.5G, the fifth generation (5G) communicationprotocols, wireless local area network (WLAN) standards, such as theIEEE 802.11 standards; and/or any other appropriate wirelesscommunication standard, and/or any other protocols either currentlyknown or to be developed in the future.

As used herein, the term “network device” refers to a device in awireless communication network via which a terminal device accesses thenetwork and receives services therefrom. The network device may refer toa base station (BS) or an access point (AP), for example, a node B(NodeB or NB), an evolved NodeB (eNodeB or eNB), a gNB, a Remote RadioUnit (RRU), a radio header (RH), a remote radio head (RRH), a relay, alow power node such as a femto, a pico, and so forth, depending on theapplied terminology and technology.

The term “terminal device” refers to any end device that may be capableof wireless communications. By way of example and not limitation, aterminal device may be referred to as user equipment (UE), a SubscriberStation (SS), a Portable Subscriber Station, a Mobile Station (MS), oran Access Terminal (AT). The terminal device may include, but notlimited to, a mobile phone, a cellular phone, a smart phone, voice overIP (VoIP) phones, wireless local loop phones, a tablet, a wearabledevice, a personal digital assistant (PDA), portable computers, desktopcomputer, image capture terminal devices such as digital cameras, gamingterminal devices, music storage and playback appliances, wearableterminal devices, vehicle-mounted wireless terminal devices, wirelessendpoints, mobile stations, laptop-embedded equipment (LEE),laptop-mounted equipment (LME), USB dongles, smart devices, wirelesscustomer-premises equipment (CPE) and the like. In the followingdescription, the terms “terminal device”, “terminal”, “user equipment”and “UE” may be used interchangeably.

The terminal device may support device-to-device (D2D) communication,for example by implementing a 3GPP standard for sidelink communication,and may in this case be referred to as a D2D communication device.

As yet another example, in an Internet of Things (IOT) scenario, aterminal device may represent a machine or other device that performsmonitoring and/or measurements, and transmits the results of suchmonitoring and/or measurements to another terminal device and/or networkequipment. The terminal device may in this case be a machine-to-machine(M2M) device, which may in a 3GPP context be referred to as amachine-type communication (MTC) device. As one particular example, theterminal device may be a UE implementing the 3GPP narrow band internetof things (NB-IoT) standard. Examples of such machines or devices aresensors, metering devices such as power meters, industrial machinery, orhome or personal appliances, for example refrigerators, televisions,personal wearables such as watches etc. In other scenarios, a terminaldevice may represent a vehicle or other equipment that is capable ofmonitoring and/or reporting on its operational status or other functionsassociated with its operation.

As used herein, a DL transmission refers to a transmission from thenetwork device to a terminal device, and an UL transmission refers to atransmission in an opposite direction.

FIG. 1 illustrates an example wireless communication network 100 inwhich embodiments of the disclosure may be implemented. As shown in FIG.1, the wireless communication network 100 may include one or morenetwork devices, for example network devices 101 and 111, which may bein a form of an eNB or gNB, providing cell 130 and cell 140respectively. It will be appreciated that the network device 101 or 111could also be in a form of a Node B, Base Transceiver Station (BTS),and/or Base Station Subsystem (BSS), AP and the like. The network device101 may provide radio connectivity to a set of terminal devices (forexample UEs 102 and 103) within a cell 130, while the network device 111may provide radio connectivity to another set of terminal devices forexample UE 104 in another cell 140 shown in FIG. 1. The network devices101 and 111 may be in different forms.

In wireless communication systems, a terminal device has to setup aconnection with a network node before transmitting any data to thenetwork node. A procedure for a terminal device to request a connectionsetup is commonly referred to as random access. In a random accessprocedure, a terminal device transmits a random access preamble (alsoreferred to as a physical random access channel (PRACH) preamble, apreamble, a random access channel (RACH) request, or Msg1) to a networkdevice. Transmission of the random access preamble may use a resourcedetermined based on a random access configuration.

Irrespective of how a PRACH design is adopted in, for example, 3GPPRadio Access Network 1 (RAN1) for a wireless system (for example NR),there may be some corresponding random access configuration (e.g.,NR-prach-ConfigIndex, or PRACH-Configuration-Index) which is broadcastedto indicate possible time and frequency configurations. In some cases,there may be PRACH radio resources configured in multiple subframes inone radio frame. Table 5.7.1-2 from 3GPP TS 36.211-v10.1.0 showingexamples for random access configurations of Frame structure type 1 isreproduced below as Table 1. More details on parameters shown in Table 1and their values may be found, for example, in 3GPP TS 36.211 v10.1.0,Section 5.7 Physical random access channel.

TABLE 1 PRACH System PRACH System Configuration Preamble frame SubframeConfiguration Preamble frame Subframe Index Format number number IndexFormat number number 0 0 Even 1 32 2 Even 1 1 0 Even 4 33 2 Even 4 2 0Even 7 34 2 Even 7 3 0 Any 1 35 2 Any 1 4 0 Any 4 36 2 Any 4 5 0 Any 737 2 Any 7 6 0 Any 1, 6 38 2 Any 1, 6 7 0 Any 2, 7 39 2 Any 2, 7 8 0 Any3, 8 40 2 Any 3, 8 9 0 Any 1, 4, 7 41 2 Any 1, 4, 7 10 0 Any 2, 5, 8 422 Any 2, 5, 8 11 0 Any 3, 6, 9 43 2 Any 3, 6, 9 12 0 Any 0, 2, 4, 6, 844 2 Any 0, 2, 4, 6, 8 13 0 Any 1, 3, 5, 7, 9 45 2 Any 1, 3, 5, 7, 9 140 Any 0, 1, 2, 3, 4, 46 N/A N/A N/A 5, 6, 7, 8, 9 15 0 Even 9 47 2 Even9 16 1 Even 1 48 3 Even 1 17 1 Even 4 49 3 Even 4 18 1 Even 7 50 3 Even7 19 1 Any 1 51 3 Any 1 20 1 Any 4 52 3 Any 4 21 1 Any 7 53 3 Any 7 22 1Any 1, 6 54 3 Any 1, 6 23 1 Any 2, 7 55 3 Any 2, 7 24 1 Any 3, 8 56 3Any 3, 8 25 1 Any 1, 4, 7 57 3 Any 1, 4, 7 26 1 Any 2, 5, 8 58 3 Any 2,5, 8 27 1 Any 3, 6, 9 59 3 Any 3, 6, 9 28 1 Any 0, 2, 4, 6, 8 60 N/A N/AN/A 29 1 Any 1, 3, 5, 7, 9 61 N/A N/A N/A 30 N/A N/A N/A 62 N/A N/A N/A31 1 Even 9 63 3 Even 9

In response to receiving the random access preamble from a terminaldevice, a network device transmits, to the terminal device a randomaccess response (RAR) message (which may also be referred to as Msg2)carrying a timing advance (TA) command to adjust the UL transmissiontiming of the terminal device. The terminal device transmits, to thenetwork device, a message 3 (which may also be referred to as Msg3)using the resource assigned/scheduled by the network device via the RARmessage. In response to the received Msg3, the network device maytransmit a contention-resolution message (which may also be referred toas Msg4) to the terminal device.

In LTE, a size of the Msg3 may be indicated via a PRACH transmission. Incurrent LTE specification, random access preambles are divided into twogroups, i.e., a first Random Access preamble group and a second RandomAccess preamble group. If the size of Msg3 is smaller than or equal to apreconfigured threshold, UE chooses a Random Access preamble from thefirst Random Access preamble group, otherwise, the UE selects a randomaccess preamble from the second Random Access preamble group. The eNBmay determine the size of Msg3 according to the detected PRACH preambleindex and allocate an UL grant to the UE so that there is certainprobability for the UE to transmit all data. That is, selection of theRandom Access preamble group provides one bit for indicating size of theMsg3.

However, inventors of the present application have observed that such arough granularity indication of the size of message 3 in LTE may not beenough for NR. In a NR system, a terminal device may transmit a smallpacket and therefore, it may be desirable that such a small packet canbe conveyed during random access, for example using Msg3. To indicate asize of a small packet carried in Msg3, a finer granularity may berequired.

In order to solve at least part of the above problems, methods,apparatuses and computer program products have been proposed herein.Some embodiments of the present disclosure provide a solutionfacilitating an efficient random access procedure. In particular, moreinformation on the size of Msg3 may be provided to the network deviceduring a RACH procedure compared with conventional RACH procedure.

For example, in some embodiments, some parameter(s) in a conventionalPRACH configuration may be reused for indication of the size of theMsg3. That is, for the dense PRACH transmission occasions shown in theabove Table 1, one may also use PRACH transmission position in time(subframe number) to indicate the size of Msg3.

In some embodiments, subframe number or system frame number (SFN) usedfor a PRACH transmission may be used to indicate the size of the Msg3.As a further enhancement, any combination of the subframe number, theSFN and the Random Access preamble of a PRACH transmission may be usedto indicate the size of the Msg3.

For illustration rather than limitation, some examples for indicatingthe size of the Msg3 during a RACH procedure are provided below. Thoughin some examples, the size of the Msg3 is indicated via the subframenumber, or the SFN of a PRACH transmission or any combination of thesubframe number, the SFN and the Random Access Preamble of the PRACHtransmission, in some other embodiments, additional parameters may beused for such indication.

Example 1: Use a Subframe Number of a PRACH Transmission to Indicate aSize of a Msg3

For this example, the size of the Msg3 is indicated using the subframenumber when the PRACH is transmitted. The subframe number is dividedinto z groups, and z−1 thresholds for the size of the Msg3 areconfigured for UE to determine the subframe number for the PRACHtransmission. Note that z may be an integer larger than 2, in someembodiments.

For instance, according to Table 1 above, when PRACH Configuration Indexis set to 6, there are two transmission opportunities in radio framesubframes 1 and 6, and the transmission opportunities are divided intotwo groups (referred to as PRACH transmission groups) according to thesubframe number of the PRACH transmission: PRACH transmissions atsubframe 1 are included into Group 0, and PRACH transmissions atsubframe 6 are included into Group 1. UEs may be configured by the basestation to transmit PRACH in subframe 1 if a size of a Msg3 is smalleror equal to a configured threshold Y bits and to transmit PRACH insubframe 6 if the size of the Msg3 is larger than the configuredthreshold Y bits.

Example 2: Use a SFN of a PRACH Transmission to Indicate a Size of aMsg3

For this example, the size of the Msg3 is indicated using the SFN whenthe PRACH is transmitted. The PRACH transmission occurrences are dividedinto z groups (referred to as PRACH transmission groups) based on theSFN, and a group index for a radio frame may be determined via SFNmodulo z, i.e., group index=mod(SFN, z). The z−1 thresholds for the sizeof the Msg3 are configured for UE to determine the SFN for the PRACHtransmission. The UE determines the PRACH transmission group accordingto a comparison between the size of the Msg3 and the z−1 thresholds forthe size of Msg3. Note that z may be an integer larger than 2, in someembodiments.

For instance, according to Table 1 above, when a PRACH ConfigurationIndex is configured to 3, a UE is allowed to transmit PRACH in subframe1 in any radio frame. It may be configured that PRACH transmissionoccurrences are divided into two groups, for example, group 0 for PRACHtransmissions in radio frames with odd SFNs, and group 1 for PRACHtransmissions in radio frames with even SFNs. A threshold of K bits forthe size the Msg3 may be configured for the UE. If the size of Msg3 issmaller than or equal to K bits, the UE may transmit the PRACH in aradio frame with a SFN from group 0; otherwise, the UE may transmit thePRACH in a radio frame with a SFN from group 1.

Example 3: Use a Combination of any of a Subframe Number, a SFN andRandom Access Preamble of PRACH Transmission to Indicate a Size of aMsg3

According to this example, the PRACH transmission occurrences aregrouped using any two or all of the subframe number, the SFN and theRandom Access preamble of PRACH transmission. PRACH transmissionoccurrences belonging to different groups (referred to as PRACHtransmission groups) indicate different sizes of the Msg3. Correspondingthresholds for the size of the Msg3 may be configured, and UE maydetermine the PRACH transmission according to a comparison between thesize of the Msg3 and the thresholds for the size of the Msg3.

For instance, according to Table 1 above, when PRACH Configuration Index6 is set, the PRACH may be transmitted in subframe 1 or 6 in any radioframe. The PRACH transmission occurrences may be divided into 4 groups,for example, PRACH transmission group a0 for PRACH transmissions insubframe 1 of a radio frame with an odd SFN, PRACH transmission group a1for PRACH transmissions in subframe 6 of a radio frame with an odd SFN,PRACH transmission group a2 for PRACH transmissions in subframe 1 of aradio frame with an even SFN, and PRACH transmission group a3 for PRACHtransmission in subframe 6 of a radio frame with an even SFN. Incorrespondence, there are 3 Msg3 threshold sizes, O0, O1, O2 (O0<O1<O2).If the size of Msg3 is smaller than or equal to O0, larger than O0 butsmaller or equal to O1, larger than O1 but smaller or equal to O2,larger than O2, the PRACH is transmitted by the UE using a resourcebelonging to group a0, a1, a2 and a3 respectively.

Similarly, other grouping scheme(s) for the size of the Msg3 may bedefined as well. For instance, the PRACH transmission occurrences may bedivided into groups based on a subframe number of the PRACH transmissionin combination of Random Access preamble grouping. When Random Accesspreambles are divided into two groups (e.g., preamble group A and B) andPRACH Configuration Index 6 is set, the PRACH transmission opportunitiesmay be divided into 4 groups: group b0 for PRACH transmission using arandom access preamble from the preamble group A in subframe 1, group b1for a PRACH transmission using a random access preamble from thepreamble group A in subframe 6, PRACH transmission group b2 for a PRACHtransmission using a random access preamble from preamble group B insubframe 1 and PRACH transmission group b3 for a PRACH transmissionusing a random access preamble from preamble group B in subframe 6. Incorrespondence, there may be 3 Msg3 threshold sizes, P0, P1, P2(P0<P1<P2). If the size of the Msg3 is smaller than or equal to P0,larger than P0 but smaller or equal to P1, larger than P1 but smaller orequal to P2, or larger than P2, the PRACH is transmitted by UE using aresource belonging to group b0, b1, b2 and b3 respectively.

For any example above, the UE shall firstly determine which PRACHtransmission group shall be used for a PRACH transmission by comparing asize of a Msg3 with preconfigured thresholds to select a PRACHtransmission group, then the UE determines a PRACH transmissionparameter(s) (identified by, for example but not limited to, a SFN, asubframe number and a Random Access preamble) within a determined PRACHtransmission group, and transmits the PRACH using the determined PRACHtransmission parameter(s).

For any example above, the base station shall firstly detect a PRACHpreamble, secondly determine a group index of the PRACH transmissionaccording to the preconfigured PRACH transmission grouping, thirdlydetermine the size of the Msg3 range according to a mapping between thePRACH transmission group and a size of a Msg3; determine an UL grantaccording to the determined size of the Msg3 range, and send the ULgrant to the UE for UL small data transmission from the UE.

The system may configure a PRACH transmission grouping scheme andparameters via either system information (SI) or a dedicated RadioResource Control (RRC) signalling. As one example, other SI may be usedto configure the parameters for PRACH transmission grouping and thecorresponding thresholds for the size of the Msg3. As another example,the parameters for PRACH transmission grouping and the correspondingthresholds for the size of the Msg3 may be transmitted to the UE via adedicated RRC signalling when the UE is configured to be in aRRC_Inactive state.

Reference is now made to FIG. 2 which shows a flowchart of a method 200in a terminal device according to an embodiment of the presentdisclosure. The terminal device may be, for example, any of the terminaldevices 102-104 shown in FIG. 1. For ease of discussions, the method 200will be described below with reference to the terminal device 102 andthe environment as described with reference to FIG. 1. However,embodiments of the present disclosure are not limited thereto and may beapplied more widely in other scenarios where similar problem exists.

As illustrated in FIG. 2, at block 210, the terminal device 102 receivesa random access configuration from a network device 101, the randomaccess configuration including information for determining a set ofcandidate subframe numbers and a set of candidate system frame numbers(SFNs) for transmitting a random access preamble. Each SFN is associatedwith a radio frame. At block 220, the terminal device 102 transmits therandom access preamble in a subframe within a radio frame. The subframeis associated with a subframe number, and the radio frame is associatedwith a system frame number. Furthermore, the subframe number is selectedfrom the set of candidate subframe numbers, and/or, the system framenumber is selected from the set of candidate system frame numbers, basedon a size of a Msg3 to be transmitted by the terminal device to thenetwork device during the random access.

The subframe number and/or the system frame number for transmitting therandom access preamble by the terminal device may be used by the networkdevice to estimate a size of a following Msg3 to be transmitted by theterminal device. Therefore, the method 200 enables the network device101 to grant a proper resource to the terminal device 102 using a RARmessage in response to the RACH preamble. The transmission and receptionof the following RAR, Msg3 and the Msg4 may be implemented according to,for example, a conventional RACH procedure specified in LTE, butembodiments are not limited thereto.

In some embodiments, the terminal device 102 may receive a furtherconfiguration for a set of thresholds with respect to the size of theMsg3 and a mapping configuration between the set of thresholds and PRACHtransmissions; and determine a PRACH transmission based on the set ofthresholds, to indicate the size of the Msg3 to the network device.

Reference is now made to FIG. 3 which shows a flowchart of a method 300in a network device according to an embodiment of the presentdisclosure. The terminal device may be, for example, any of the networkdevices 101 and 111 shown in FIG. 1. For ease of discussions, the method300 will be described below with reference to the network device 101 andthe environment as described with reference to FIG. 1. However,embodiments of the present disclosure are not limited thereto and may beapplied more widely in other scenarios where similar problem exists.

As illustrated in FIG. 3, at block 310, the network device 101 transmitsa random access configuration to a terminal device (e.g., terminaldevice 102). The random access configuration includes information fordetermining a set of candidate subframe numbers and a set of candidatesystem frame numbers for transmitting a random access preamble. At block320, the network device 101 receives, from the terminal device, a randomaccess preamble in a subframe within a radio frame, wherein the subframeis associated with a subframe number, and the radio frame is associatedwith a system frame number. In addition, the subframe number is selectedby the terminal device from the set of candidate subframe numbers,and/or, the system frame number is selected from the set of candidatesystem frame numbers, based on a size of a Msg3 to be transmitted by theterminal device 102 to the network device 101 during the random access.At block 330, the network device 101 determines the size of the Msg3 tobe transmitted by the terminal device during the random access, based onat least one of the subframe number and the system frame number. Thedetermination enables the network device 101 to grant a proper resourceto the terminal device for transmitting the Msg3.

FIG. 4 illustrates a simplified block diagram of an apparatus 410 thatmay be embodied in/as a network device, for example, the network device101 or 111 shown in FIG. 1, and an apparatus 420 that may be embodiedin/as a terminal device, for example, any of the terminal devices102-104 shown in FIG. 1.

The apparatus 410 may include one or more processors 411, such as a dataprocessor (DP) and one or more memories (MEM) 812 coupled to theprocessor 411. The apparatus 410 may further include a transmitter TXand receiver RX 413 coupled to the processor 411. The MEM 412 may benon-transitory machine readable storage medium and it may store aprogram or a computer program product (PROG) 414. The PROG 414 mayinclude instructions that, when executed on the associated processor411, enable the apparatus 410 to operate in accordance with theembodiments of the present disclosure, for example to perform the method300. A combination of the one or more processors 411 and the one or moreMEMs 412 may form processing means 415 adapted to implement variousembodiments of the present disclosure.

The apparatus 420 includes one or more processors 421, such as a DP, andone or more MEMs 422 coupled to the processor 421. The apparatus 420 mayfurther include a suitable TX/RX 423 coupled to the processor 421. TheMEM 422 may be non-transitory machine readable storage medium and it maystore a PROG 424. The PROG 424 may include instructions that, whenexecuted on the associated processor 421, enable the apparatus 420 tooperate in accordance with the embodiments of the present disclosure,for example to perform the method 200. A combination of the one or moreprocessors 421 and the one or more MEMs 422 may form processing means825 adapted to implement various embodiments of the present disclosure.

Various embodiments of the present disclosure may be implemented bycomputer program or computer program product executable by one or moreof the processors 411 and 421, software, firmware, hardware or in acombination thereof.

The MEMs 412 and 422 may be of any type suitable to the local technicalenvironment and may be implemented using any suitable data storagetechnology, such as semiconductor based memory terminal devices,magnetic memory terminal devices and systems, optical memory terminaldevices and systems, fixed memory and removable memory, as non-limitingexamples.

The processors 411 and 421 may be of any type suitable to the localtechnical environment, and may include one or more of general purposecomputers, special purpose computers, microprocessors, digital signalprocessors DSPs and processors based on multicore processorarchitecture, as non-limiting examples.

Although some of the above description is made in the context of awireless communication system shown in FIG. 1, it should not beconstrued as limiting the spirit and scope of the present disclosure.The principle and concept of the present disclosure may be moregenerally applicable to other scenarios.

In addition, the present disclosure may also provide computer readablestorage medium such as a memory containing the computer program orcomputer program product as mentioned above, which includesmachine-readable media and machine-readable transmission media. Themachine-readable media may also be called computer-readable media, andmay include machine-readable storage media, for example, magnetic disks,magnetic tape, optical disks, phase change memory, or an electronicmemory terminal device like a random access memory (RAM), read onlymemory (ROM), flash memory devices, CD-ROM, DVD, Blue-ray disc and thelike. The machine-readable transmission media may also be called acarrier, and may include, for example, electrical, optical, radio,acoustical or other form of propagated signals—such as carrier waves,infrared signals, and the like.

The techniques described herein may be implemented by various means sothat an apparatus implementing one or more functions of a correspondingapparatus described with an embodiment includes not only prior artmeans, but also means for implementing the one or more functions of thecorresponding apparatus described with the embodiment and it may includeseparate means for each separate function, or means that may beconfigured to perform two or more functions. For example, thesetechniques may be implemented in hardware (one or more apparatuses),firmware (one or more apparatuses), software (one or more modules), orcombinations thereof. For a firmware or software, implementation may bemade through modules (for example, procedures, functions, and so on)that perform the functions described herein.

Example embodiments herein have been described above with reference toblock diagrams and flowchart illustrations of methods and apparatuses.It will be understood that each block of the block diagrams andflowchart illustrations, and combinations of blocks in the blockdiagrams and flowchart illustrations, respectively, can be implementedby various means including hardware, software, firmware, and acombination thereof. For example, in one embodiment, each block of theblock diagrams and flowchart illustrations, and combinations of blocksin the block diagrams and flowchart illustrations can be implemented bycomputer program or computer program product which includes computerprogram instructions. These computer program instructions may be loadedonto a general purpose computer, special purpose computer, or otherprogrammable data processing apparatus to produce a machine, such thatthe instructions which execute on the computer or other programmabledata processing apparatus create means for implementing the functionsspecified in the flowchart block or blocks.

Further, while operations are depicted in a particular order, thisshould not be understood as requiring that such operations be performedin the particular order shown or in sequential order, or that allillustrated operations be performed, to achieve desirable results. Incertain circumstances, multitasking and parallel processing may beadvantageous. Likewise, while several specific implementation detailsare contained in the above discussions, these should not be construed aslimitations on the scope of the subject matter described herein, butrather as descriptions of features that may be specific to particularembodiments. Certain features that are described in this specificationin the context of separate embodiments can also be implemented incombination in a single embodiment. Conversely, various features thatare described in the context of a single embodiment can also beimplemented in multiple embodiments separately or in any suitablesub-combination. Moreover, although features may be described above asacting in certain combinations and even initially claimed as such, oneor more features from a claimed combination can in some cases be excisedfrom the combination, and the claimed combination may be directed to asub-combination or variation of a sub-combination.

It will be obvious to a person skilled in the art that, as thetechnology advances, the inventive concept can be implemented in variousways. The above described embodiments are given for describing ratherthan limiting the disclosure, and it is to be understood thatmodifications and variations may be resorted to without departing fromthe spirit and scope of the disclosure as those skilled in the artreadily understand. Such modifications and variations are considered tobe within the scope of the disclosure and the appended claims. Theprotection scope of the disclosure is defined by the accompanyingclaims.

What is claimed is:
 1. A method in a terminal device for random accessin a wireless communication network, the method comprising: receiving arandom access configuration from a network device, the random accessconfiguration including information for determining a set of candidatesubframe numbers and a set of candidate system frame numbers fortransmitting a random access preamble; and transmitting the randomaccess preamble in a subframe within a radio frame, the subframe beingassociated with a subframe number, and the radio frame being associatedwith a system frame number; wherein the subframe number is selected fromthe set of candidate subframe numbers, and/or, the system frame numberis selected from the set of candidate system frame numbers, based on asize of a Message 3, Msg3, to be transmitted by the terminal device tothe network device during the random access.
 2. The method according toclaim 1, wherein the random access preamble is selected from a set ofcandidate preambles based on the size of the Msg3.
 3. The methodaccording to claim 1, further comprising: receiving a furtherconfiguration for a set of thresholds with respect to the size of theMsg3 and a mapping configuration between the set of thresholds and PRACHtransmissions; and determining a PRACH transmission based on the set ofthresholds, to indicate the size of the Msg3 to the network device.
 4. Amethod in a network device for random access in a wireless communicationnetwork, the method comprising: transmitting a random accessconfiguration to a terminal device, the random access configurationincluding information for determining a set of candidate subframenumbers and a set of candidate system frame numbers for transmitting arandom access preamble; receiving, from the terminal device, a randomaccess preamble in a subframe within a radio frame, the subframe beingassociated with a subframe number, and the radio frame being associatedwith a system frame number, wherein the subframe number is selected fromthe set of candidate subframe numbers, and/or, the system frame numberis selected from the set of candidate system frame numbers, based on asize of a Message 3, Msg3, to be transmitted by the terminal device tothe network device during the random access; and determining the size ofthe Msg3, to be transmitted by the terminal device during the randomaccess, based on at least one of the subframe number and the systemframe number.
 5. The method according to claim 4, wherein determiningthe size of the Msg3 comprises: determining the size of the Msg3 furtherbased on the random access preamble.
 6. An apparatus in a terminaldevice for random access in a wireless communication network, theapparatus comprising a processor and a memory, said memory containinginstructions executable by said processor whereby said apparatus isoperative to: receive a random access configuration from a networkdevice, the random access configuration indicating a set of candidatesubframe numbers and a set of candidate system frame numbers fortransmitting a random access preamble; and transmit the random accesspreamble in a subframe within a radio frame, the subframe beingassociated with a subframe number, and the radio frame being associatedwith a system frame number; wherein the subframe number is selected fromthe set of candidate subframe numbers, and/or, the system frame numberis selected from the set of candidate system frame numbers, based on asize of a Message 3, Msg3, to be transmitted by the terminal device tothe network device during the random access.
 7. An apparatus in anetwork device for random access in a wireless communication network,the apparatus comprising a processor and a memory, said memorycontaining instructions executable by said processor whereby saidapparatus is operative to: transmit a random access configuration to aterminal device, the random access configuration indicating a set ofcandidate subframe numbers and a set of candidate system frame numbersfor transmitting a random access preamble; receive, from the terminaldevice, a random access preamble in a subframe within a radio frame, thesubframe being associated with a subframe number, and the radio framebeing associated with a system frame number; wherein the subframe numberis selected from the set of candidate subframe numbers, and/or, thesystem frame number is selected from the set of candidate system framenumbers, based on a size of a Message 3, Msg3, to be transmitted by theterminal device to the network device during the random access, anddetermine the size of the Msg3, to be transmitted by the terminal deviceduring the random access, based on at least one of the subframe numberand the system frame number.